A123 Systems has been the subject of much consternation, as one of the companies which received heavy funding from the U.S. government, and a failed investment bid from Wanxiang, before going bankrupt in October last year.

There have been some concerns that a buy-out from Wanxiang would lead to U.S. automobile tech secrets finding their way into China.

However, it's likely the deal was approved due to the company's history of investing in U.S. firms--the company generates around $1 billion in U.S. revenue supplying parts to GM and Ford. It has also bought or invested in as many as 20 other U.S. companies, many of which were in bankruptcy.

Not included in the deal is A123's defense contracts. These have been sold separately to Navitas Systems for $2.25 million.

The money raised from December's auction will go towards paying off A123's debts, which currently stand at about $376 million.

The finalized sale won't come too soon for Fisker Automotive, which delayed production due to a shortage of A123 battery packs for its Karma luxury sedan.